Traditionally, windows and glazed doors have been fabricated from wood. Wood is a better insulator than metal, hence there is much less heat loss through a wooden window sash and frame than through a metal one. Furthermore, condensation rarely forms on wood windows. Wooden windows and doors also are easily painted or stained to provide an aesthetically pleasing appearance compatible with a building's interior decoration.
Traditional window glazing involves setting a glass pane or light into a lip cut in the wooden window sash, fixing the light to the sash with a number of nails or glazing points and sealing the lights to the sash with a putty fill. A more consistent appearance may be achieved by substituting a wooden molded glazing bead for the putty. Improved insulating properties have been achieved by using double thicknesses of glass separated by a sealed metal spacer. Wooden beads, while attractive, require upkeep and painting, and are time consuming to fit and install.
Glazing systems employing vinyl glazing strips have taken a number of forms. A vinyl glazing strip with compressible barbs may be inserted into a wooden kerf above the outer window pane to bear against the glass light and compressively seal the light to the sash. Another vinyl glazing involves an extruded vinyl boot which surrounds the edges of both panes of insulated glass and which fits in a wide slot in the sash. However, although vinyl does not require painting, it is subject to decomposition upon exposure to sunlight which results in an unattractive appearance and necessitates eventual replacement.
Wooden windows which have an exterior cladding of aluminum are well known and provide an attractive and low maintenance exterior appearance. Because of aluminum's limitated flexibility, exterior aluminum glazing strips have been employed with an elastic sealant such as butyl tape. Such a system may be costly to apply, requiring re-application of a new sealant each time the aluminum strip is removed.
Traditional wooden windows have sashes divided by one or more vertical and horizontal muntin bars into a number of smaller aperatures which are each individually glazed. These divided lights, each at a slightly different angle, have perceptibly differing reflections and surface conditions which produce an aesthetically desirable effect which cannot fully be duplicated by muntin bar assemblies which are placed over a single light.
Window glass is occasionally subject to breakage due to storms, settling and vandalism. Windows glazed with Putty or wood strips, and those encased in vinyl boots, are usually damaged when the broken glass is removed.
What is needed is a glazing system for wooden windows and doors which may be quickly installed and replaceably removed, which presents a low maintenance and attractive exterior and which will economically accommodate divided lights.